o'clock
adv. timeadv. used after a number from one to twelve to say exactly what hour it is. You only use this when the time is exactly on the hour, with no extra minutes.
adv. used after a cardinal number to specify the hour of the day. Functions as a post-modifier to a numeral in time expressions.
The meeting starts at nine o'clock tomorrow morning.
I usually finish my shift at five o'clock and head straight to the gym.
The historic tower bell rings loudly every day at twelve o'clock, signaling the start of the lunch hour for the entire village.
Shortened form of "of the clock", from Middle English of the clokke [from late 14th c.].
Only follows numbers 1 through 12; never used with 'a.m.', 'p.m.', or when minutes are included.
It is 10:30 o'clock.It is 10:30.O'clock is only used for exact hours, not when minutes are specified.